Flat uniform transmission line having electromagnetic shielding function

ABSTRACT

Disclosed herein is a flat uniform transmission line having an electromagnetic shielding function. The flat uniform transmission line includes a strip transmission line, an insulating layer, and electromagnetic shielding layers. The strip transmission line is formed on a dielectric layer made of functional polymer material, and includes a plurality of strip lines. The plurality of strip lines are configured to be a ground line, or to transmit signals. The insulating layer is formed on the strip transmission line. The electromagnetic shielding layers are respectively formed on the insulating layer and beneath the strip transmission line.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a flat uniform transmission line, inwhich a strip transmission line, an insulating layer and anelectromagnetic shielding layer are formed in a stacked structure,thereby making a flat and uniform transmission line, so that it can beembedded in both indoor and outdoor floors in buildings and thus can beused instead of an existing power supply cable and an existingtransmission cable, with the result that wiring between devices, whichis becoming increasingly complicated, can be simply constructed.

2. Description of the Related Art

In regard to the prior art, in a non-uniform transmission line and amethod of fabricating the same, which are shown in FIG. 1, a non-uniformflat transmission line 1 is provided, wherein transmission lines 3 and 5are respectively disposed on and beneath a dielectric layer 4 in orderto make the non-uniform flat transmission line 1 flat, and insulatinglayers 2 and 6 are respectively disposed on and beneath the transmissionlines 3 and 5, thereby enabling it to maintain its function overlong-distances, which is the characteristic of a twisted-pair cable(U.S. Pat. No. 6,774,741).

However, the non-uniform flat transmission line has limitationsregarding signal transmission distance and a high loss of transmissionsignal due to noise loss caused by non-uniformity and discontinuity,which are the structural characteristics of the twisted-pair cableformed on and beneath the dielectric layer. As a result, a problemarises in that the transmission of signals is limited.

Furthermore, the non-uniform flat transmission line is mainly used onlyfor the transmission of low frequency signals, and has a problem in thatit cannot realize the same transmission characteristics as a coaxialcable, which is mainly used for high frequency signal transmission.

In addition, the non-uniform flat transmission line is problematic inthat it is easily exposed to various kinds of noise because there is noelectromagnetic shielding function.

Accordingly, the non-uniform flat transmission line has problems in thatlarge transmission losses occur in a transmission band because it isexposed to noise signals, and thus the ability to eliminate common modenoise is limited, it is difficult to implement a flat transmission linehaving a characteristic in which a single signal is transmitted througha coaxial cable, and it does not have an electromagnetic shieldingfunction necessary for an electrical wire transmission line.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made to solve the aboveproblems, and an object of the present invention is to provide a flatuniform transmission line in which a strip transmission line, aninsulating layer and an electromagnetic shielding layer are formed in astacked structure, thereby making a transmission line flat and uniform,so that it can replace a conventional twisted-pair cable and a coaxialcable.

Another object of the present invention is to provide a flat uniformtransmission line which has low-loss transmission characteristics in anoperating frequency band because the strip lines of strip transmissionlines are formed on and beneath a dielectric layer, thereby distributingimpedance, the overall size of the flat uniform transmission line isminimized, and an electromagnetic shielding function can be realizedthrough the incorporation of electromagnetic shielding layers.

In order to accomplish the above objects, the present invention providesa flat uniform transmission line having an electromagnetic shieldingfunction, which includes a strip transmission line formed on adielectric layer made of functional polymer material, the striptransmission line comprising a plurality of strip lines, the pluralityof strip lines including a first strip line configured to be a groundline, a second strip line supplied with a single signal, and a thirdstrip line configured to be a ground line; an insulating layer formed onthe strip transmission line; and electromagnetic shielding layersrespectively formed on the insulating layer and beneath the striptransmission line.

Additionally, the present invention provides a flat uniform transmissionline having an electromagnetic shielding function, including a firststrip transmission line formed on a dielectric layer made of functionalpolymer material in order to transmit signals, the first striptransmission line comprising a plurality of strip lines; a second striptransmission line formed beneath the dielectric layer in order totransmit signals, the second strip transmission line comprising aplurality of strip lines; insulating layers respectively formed on thefirst strip transmission line and beneath the second strip transmissionline; and electromagnetic shielding layers respectively formed on theupper insulating layer and beneath the lower insulating layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram showing the construction of a conventionalnon-uniform flat transmission line;

FIG. 2A is a diagram showing the construction of a flat uniformtransmission line according to a first embodiment of the presentinvention;

FIG. 2B is a sectional view of the flat uniform transmission line ofFIG. 2A;

FIG. 3A is a diagram showing the construction of a flat uniformtransmission line according to a second embodiment of the presentinvention;

FIG. 3B is a sectional view of the flat uniform transmission line ofFIG. 3A;

FIG. 4A is a diagram showing the construction of a flat uniformtransmission line according to a third embodiment of the presentinvention;

FIG. 4B is a sectional view of the flat uniform transmission line ofFIG. 4A;

FIG. 5A is a diagram showing the construction of a flat uniformtransmission line according to a fourth embodiment of the presentinvention;

FIG. 5B is a sectional view of the flat uniform transmission line ofFIG. 5A;

FIG. 6A is a diagram showing the construction of a flat uniformtransmission line according to a fifth embodiment of the presentinvention;

FIG. 6B is a sectional view of the flat uniform transmission line ofFIG. 6A;

FIG. 7 is a diagram showing differential impedance characteristics basedon FIG. 4A of the present invention;

FIG. 8 is a diagram showing loss and reflection coefficientcharacteristics based on FIG. 4A of the present invention;

FIG. 9 is a diagram showing single impedance characteristics based onFIG. 5A of the present invention; and

FIG. 10 is a diagram showing insertion loss and the reflectioncoefficient characteristics based on FIG. 5A of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a flat uniform transmission line having an electromagneticshielding function according to the present invention is described indetail in connection with preferred embodiments and with reference tothe accompanying drawings. However, the present invention is not limitedto the following embodiments.

FIG. 2A is a diagram showing the construction of a flat uniformtransmission line according to a first embodiment of the presentinvention. FIG. 2B is a sectional view of the flat uniform transmissionline of FIG. 2A. FIG. 2A shows the flat transmission line in which twostrip lines 111 and 112 are formed in the same cross-section of adielectric layer 105 so that the flat transmission line hascharacteristics like those of a conventional twisted-pair cable whichtransmits differential signals.

The flat uniform transmission line 10 according to the first embodimentof FIG. 2A includes a strip transmission line 100, configured such thatthe two strip lines 111 and 112 are formed on the dielectric layer 105made of functional polymer material so as to transmit signals, aninsulating layer 200 formed on the strip transmission line 100 so as toinsulate the strip transmission line 100, and electromagnetic shieldinglayers 300 respectively formed on the insulating layer 200 and beneaththe strip transmission line 100.

The strip transmission line 100 has a structure in which the two striplines 111 and 112 are formed on the dielectric layer 105 so as totransmit signals.

The dielectric layer 105 has a constant thickness within a range of 0.1to 5000 μm, and is made of any one material selected from the groupconsisting of polystyrene, polyethylene, polyester, polyimide andpolypropylene, which have specific relative permittivity within a rangeof 1 to 10. The material is flexible, and thus the entire flat uniformtransmission line has a flexible structure and flexible characteristic.

The two strip lines 111 and 112 are formed on the dielectric layer 105,and include a first strip line 111 and a second strip line 112 made ofany one material selected from the group consisting of polysilicon,ceramic, carbon fiber, conductive ink and conductive paste. A pluralityof strip transmission lines 100, each including the first strip line 111and the second strip line 112 in a group, may be provided.

The first and second strip lines 111 and 112 are spaced apart from eachother at a regular interval along the length of the strip transmissionline 100, and are formed parallel to each other. Even if the flatuniform transmission line 10 is bent, the regular interval between thefirst and second strip lines 111 and 112 is kept constant along thestrip transmission line 100.

Furthermore, first negative and positive differential signals areapplied to the strip transmission line 100. More particularly, the firstnegative differential signal is applied to the first strip line 111, andthe first positive differential signal is applied to the second stripline 112.

The insulating layer 200 is formed on the strip transmission line 100,and functions as a coating for insulating the first and second striplines 111 and 112 from the outside. The insulating layer 200 may be madeof any one material selected from among materials having the samecharacteristics as those of the dielectric layer 105.

The electromagnetic shielding layer 300 functions to block not onlyelectromagnetic waves radiated from the strip transmission line 100 butalso external noise. More particularly, the electromagnetic shieldinglayer 300 includes a first electromagnetic shielding layer 310 formed onthe insulating layer 200 and a second electromagnetic shielding layer320 formed beneath the strip transmission line 100.

Here, the first electromagnetic shielding layer 310 and the secondelectromagnetic shielding layer 320 are each formed by producing anelectrically conductive polymer coating composition in such a way as toadd a polymer binder, a thickener, a disperser, an adhesive, a lubricantand a solvent to electrically conductive polymer, such as polythiophene,forming a coating having a thickness within a range of 0.1 to 10 μm onthe electrically conductive polymer coating composition using a gravure,offset, kiss bar, knife, Meyer bar or coma method, and then leaving thecoated polymer coating composition at a temperature within a range of 50to 250 degrees Celsius for a period within a range of about 30 secondsto 1 hour, so that a transparent electrically conductive polymer coatinglayer is formed on the insulating layer 200 or beneath the striptransmission line 100 while the electrically conductive polymer coatingcomposition is volatilized, thus forming the first electromagneticshielding layer 310 or the second electromagnetic shielding layer 320.

In another method, the first electromagnetic shielding layer 310 and thesecond electromagnetic shielding layer 320 are each formed by applying asolution, in which an electrically conductive polymer monomer, anoxidizer and a dopant are mixed together, to the top of the insulatinglayer 200 or the bottom of the strip transmission line 100, forming anelectrically conductive polymer coating layer so as to heat the appliedsolution, and drying the electrically conductive polymer coating layer.

FIG. 3A is a diagram showing the construction of a flat uniformtransmission line 10-1 according to a second embodiment of the presentinvention. FIG. 3B is a sectional view of the flat uniform transmissionline 10-1 of FIG. 3A. As shown in the drawings, FIG. 3A shows a flattransmission line in which three strip lines 111-1 to 113-1 are formedin the same cross-section of a dielectric layer 105-1 so that it hascharacteristics like those of a conventional coaxial cable whichtransmits a single signal.

The flat uniform transmission line 10-1 according to the secondembodiment of FIG. 3A has a structure in which a single signal isapplied to the strip transmission line 100 of FIG. 2A. Since theelements of the flat uniform transmission line 10-1, which are the sameas those of FIG. 2A, have the same characteristics, detaileddescriptions thereof are omitted here.

Accordingly, as shown in FIG. 3A, a strip transmission line 100-1 isproduced by forming the three strip lines 111-1 to 113-1 fortransmitting signals on the dielectric layer 105-1.

The three strip lines 111-1 to 113-1 are formed on the dielectric layer105-1, and include a first strip line 111-1, a second strip line 112-1and a third strip line 113-1. The three strip lines 111-1 to 113-1 maybe made of any one material selected from among the materials having thesame characteristics as those of the two strip lines 111 and 112 of FIG.2A.

The first to third strip lines 111-1 to 113-1 are spaced apart from oneanother at regular intervals along the length of the strip transmissionline 100-1, and are formed parallel to one another. Even if the flatuniform transmission line 10-1 is bent, the regular intervals betweenthe first to third strip transmission lines 111-1 to 113-1 are keptconstant along the strip transmission line 100-1.

Furthermore, the strip transmission line 100-1 is supplied with a singlesignal. More particularly, the first strip line 111-1 is a ground line,the second strip line 112-1 is supplied with a single signal, and thethird strip line 113-1 becomes a ground line, thus forming a CoplanarWaveguide (CPW) structure. Furthermore, a plurality of striptransmission lines 100-1, each including the first strip line 111-1, thesecond strip line 112-1 and the third strip line 113-1 in a group, maybe provided.

As described above, since the remaining elements are the same and havethe same characteristics as those of FIG. 2, detailed descriptionsthereof are omitted here.

FIG. 4A is a diagram showing the construction of a flat uniformtransmission line 40 according to a third embodiment of the presentinvention. FIG. 4B is a sectional view of the flat uniform transmissionline 40 of FIG. 4A. FIG. 4B shows the flat uniform transmission line 40in which strip lines are constructed in a double-layer fashion in theflat uniform transmission line 10 having characteristics like those of aprior art twisted-pair cable which transmits differential signals, as inFIG. 2A.

As shown in FIG. 4A, the flat uniform transmission line 40 includes afirst strip transmission line 420, in which a plurality of strip linesis formed on a dielectric layer made of functional polymer material soas to transmit signals, a second strip transmission line 430 in which aplurality of strip lines is formed beneath the dielectric layer so as totransmit signals, insulating layers 500 which are respectively formed onthe first strip transmission line 420 and beneath the second striptransmission line 430, and electromagnetic shielding layers 600 whichare respectively formed on the insulating layer 500 and beneath theinsulating layer 500.

The first strip transmission line 420 has a structure in which fivestrip lines 421˜425 are formed on a dielectric layer 405 so as totransmit signals.

More particularly, the first strip transmission line 420 includes afirst strip line 421, a second strip line 422, a third strip line 423, afourth strip line 424, and a fifth strip line 425.

The second strip transmission line 430 has a structure in which fivestrip lines 431˜435 are formed beneath the dielectric layer 405 so as totransmit signals.

More particularly, the second strip transmission line 430 includes afirst strip line 431, a second strip line 432, a third strip line 433, afourth strip line 434, and a fifth strip line 435.

Accordingly, the first and second strip transmission lines 420 and 430are respectively formed on the dielectric layer 405 and beneath thedielectric layer 405, thereby minimizing the overall size of the flatuniform transmission line 40 and realizing broadband impedancecharacteristics.

Furthermore, the strip lines 421˜425 or 431˜435, constituting the firstand second strip transmission lines 420 and 430, have a constant widthand thickness. The strip lines 421˜425 or 431˜435 are spaced apart fromone another at regular intervals along the length of the first andsecond strip transmission lines 420 and 430, and are formed parallel toone another. Even if the flat uniform transmission line 40 is bent, theregular intervals between the plurality of strip lines 421˜425 or431˜435 are kept constant along the first or second strip transmissionline 420 or 430.

The first and second strip transmission lines 420 and 430 arerespectively supplied with first negative/positive differential signalsand second negative/positive differential signals at the same time. Moreparticularly, the first strip line 421 of the first strip transmissionline 420 and the first strip line 431 of the second strip transmissionline 430 are supplied with the first negative differential signal at thesame time, the second strip line 422 of the first strip transmissionline 420 and the second strip line 432 of the second strip transmissionline 430 are supplied with the first positive differential signal at thesame time, and the third strip line 423 of the first strip transmissionline 420 and the third strip line 433 of the second strip transmissionline 430 are ground lines. Furthermore, the fourth strip line 424 of thefirst strip transmission line 420 and the fourth strip line 434 of thesecond strip transmission line 430 are supplied with the second negativedifferential signal at the same time, and the fifth strip line 425 ofthe first strip transmission line 420 and the fifth strip line 435 ofthe second strip transmission line 430 are supplied with the secondpositive differential signal at the same time.

The strip lines 421˜425 and 431˜435, constituting the first and secondstrip transmission lines 420 and 430, are made of any one materialselected from the group consisting of metal, polysilicon, ceramic,carbon fiber, conductive ink, and conductive paste.

The dielectric layer 405 has a constant thickness within a range of 0.1to 5000 μm, and is made of any one material selected from the groupconsisting of functional polymer materials, including polystyrene,polyethylene, polyester, polyimide and polypropylene, which havespecific relative permittivity within a range of 1 to 10. Since thematerials have a flexible property, the entire flat uniform transmissionline 40 also has a flexible structure and a flexible property.

The insulating layers 500 function as coatings for insulating the firstand second strip transmission lines 420 and 430, and include a firstinsulating layer 510 formed on the first strip transmission line 420 anda second insulating layer 520 formed beneath the second strip line 430.The insulating layers 500 may be made of any one material selected fromamong materials having the same characteristics as those of thedielectric layer 405.

The electromagnetic shielding layers 600 are respectively formed on theinsulating layers 500 and beneath the insulating layers 500, andfunction to block not only electromagnetic waves radiated from the firstand second strip transmission lines 420 and 430, but also externalnoise.

More particularly, the electromagnetic shielding layers 600 include afirst electromagnetic shielding layer 610, formed on the firstinsulating layer 510, and a second electromagnetic shielding layer 620,formed beneath the second insulating layer 520.

Here, the first electromagnetic shielding layer 610 and the secondelectromagnetic shielding layer 620 are each formed by producing anelectrically conductive polymer coating composition in such a way as toadd a polymer binder, a thickener, a disperser, an adhesive, alubricant, and a solvent to an electrically conductive polymer, such aspolythiophene, forming a coating having a thickness within a range of0.1 to 10 μm on the electrically conductive polymer coating compositionusing a gravure, offset, kiss bar, knife, Meyer bar or coma method, andthen leaving the coated polymer coating composition at a temperaturewithin a range of 50 to 250 degrees Celsius for a period within a rangeof about 30 seconds to 1 hour, so that a transparent electricallyconductive polymer coating layer is formed on the first insulating layer510 or beneath the second insulating layer 520 while the electricallyconductive polymer coating composition is volatilized, and forms thefirst electromagnetic shielding layer 610 or the second electromagneticshielding layer 620.

In another method, the first electromagnetic shielding layer 610 and thesecond electromagnetic shielding layer 620 are each formed by applying asolution, in which an electrically conductive polymer monomer, anoxidizer and a dopant are mixed together, to the top of the firstinsulating layer 510 or the bottom of the second insulating layer 520,forming an electrically conductive polymer coating layer in such a wayas to heat the coated solution, and drying the electrically conductivepolymer coating layer.

More particularly, in order to promote an understanding of the presentinvention, detailed specifications of respective elements of FIG. 4Awill be described below.

The dielectric layer 405 is polyethylene functional polymer materialhaving a relative permittivity of 8, a thickness of 0.05 mm and a widthof 50 mm.

The strip lines 421˜425 and 431˜435, constituting the first and secondstrip transmission lines 420 and 430, are made of copper (Cu), and havea thickness of 0.01 mm and a width of 8 mm. The regular intervalsbetween the strip lines 421˜-425 and 431˜435 are 1 mm.

The insulating layer 500 is polyethylene functional polymer materialhaving a thickness of 0.05 mm and a width of 50 mm.

The electromagnetic shielding layer 600 is formed of an ultra-thin filmhaving a thickness equal to or less than 5 μm, and is made of anelectrically conductive polymer material having a surface resistancewithin a range of 0.01 to 10E1 Ω/cm.

Here, the above-described specifications of the flat uniformtransmission line are set forth to promote an understanding of thepresent invention through the embodiments, and the present invention isnot limited to the above-described specifications. The characteristicsof the flat uniform transmission lines of FIGS. 7 and 8, which will bedescribed later, are characteristics that were analyzed and measuredusing the flat uniform transmission line 40 designed according to theabove-described specifications described with reference to FIG. 4A.

FIG. 5A is a diagram showing the construction of a flat uniformtransmission line 40-1 according to a fourth embodiment of the presentinvention. FIG. 5B is a sectional view of the flat uniform transmissionline 40-1 of FIG. 5A. FIG. 5B shows the flat uniform transmission line40-1 in which strip lines are constructed in a double-layer fashion inthe flat uniform transmission line 10-1 having characteristics likethose of a prior art coaxial cable which transmits a single signal, asin FIG. 3A.

The flat uniform transmission line 40-1 according to the fourthembodiment of FIG. 5A has a structure in which two single signals areapplied to the first and second strip transmission lines 420 and 430 ofFIG. 4A at the same time. Since the elements of the flat uniformtransmission line 40-1, which are the same as those of FIG. 4A, have thesame characteristics, detailed descriptions thereof are omitted here.

As shown in FIG. 5A, first and second strip transmission lines 420-1 and420-2 include ten strip lines 421-1˜425-1 and 431-1˜435-1 fortransmitting signals, which are formed on or beneath a dielectric layer405-1.

The first strip transmission line 420-1 is formed on the dielectriclayer 405-1, and includes a first strip line 421-1, a second strip line422-1, a third strip line 423-1, a fourth strip line 424-1 and a fifthstrip line 425-1.

The second strip transmission line 430-1 is formed beneath thedielectric layer 405-1, and includes a first strip line 431-1, a secondstrip line 432-1, a third strip line 433-1, a fourth strip line 434-1and a fifth strip line 435-1.

Accordingly, the first and second strip transmission lines 420-1 and430-1 are respectively formed on the dielectric layer 405-1 and beneaththe dielectric layer 405-1, thereby minimizing the overall size of theflat uniform transmission line 40-1 and realizing broadband impedancecharacteristics.

Furthermore, the plurality of strip lines 421-1˜425-1 and 431-1˜435-1,constituting the first and second strip transmission lines 420-1 and430-1, have a constant width and thickness. The strip lines 421-1˜425-1and 431-1˜435-1 are spaced apart from one another at regular intervalsalong the length of the first and second strip transmission lines 420-1and 430-1, and are formed parallel to one another. Even if the flatuniform transmission line 40-1 is bent, the regular intervals betweenthe plurality of strip lines 421-1˜425-1 and 431-1˜435-1 are keptconstant along the first and second strip transmission lines 420-1 and430-1.

The first and second strip transmission lines 420-1 and 430-1 arerespectively supplied with a first single signal and a second singlesignal at the same time. More particularly, the first strip line 421-1of the first strip transmission line 420-1 and the first strip line431-1 of the second strip transmission line 430-1 are ground lines, thesecond strip line 422-1 of the first strip transmission line 420-1 andthe second strip line 432-1 of the second strip transmission line 430-1are supplied with the first single signal at the same time, and thethird strip line 423-1 of the first strip transmission line 420-1 andthe third strip line 433-1 of the second strip transmission line 430-1are ground lines. Furthermore, the fourth strip line 424-1 of the firststrip transmission line 420-1 and the fourth strip line 434-1 of thesecond strip transmission line 430-1 are supplied with the second singlesignal at the same time, and the fifth strip line 425-1 of the firststrip transmission line 420-1 and the fifth strip line 435-1 of thesecond strip transmission line 430-1 are ground lines.

The first and second strip transmission lines 420-1 and 430-1 may bemade of any one material selected from among materials having the samecharacteristics as those of the first and second strip transmissionlines 420 and 430 of FIG. 4A.

As described above, since the remaining elements are the same and havethe same characteristics as those of FIG. 4A, detailed descriptionsthereof are omitted here.

More particularly, in order to promote an understanding of the presentinvention, detailed specifications of respective elements of FIG. 5Awill be described below.

The dielectric layer 405-1 is a polyethylene functional polymer materialhaving a relative permittivity of 8, a thickness of 0.05 mm and a widthof 50 mm.

The strip lines 421-1˜425-1 and 431-1˜435-1, which constitute the firstand second strip transmission lines 420-1 and 430-1, are made of copper(Cu), and have a thickness of 0.01 mm and a width of 8 mm. The intervalbetween the strip lines 421-1˜425-1 and 431-1˜435-1 is 1 mm.

The insulating layer 500-1 is a polyethylene functional polymer materialhaving a thickness of 0.05 mm and a width of 50 mm.

The electromagnetic shielding layer 600-1 is formed of an ultra-thinfilm having a thickness equal to or less than 5 μm, and is made of anelectrically conductive polymer material having a surface resistancewithin a range of 0.01 to 10E1 Ω/cm.

Here, the above-described specifications of the flat uniformtransmission line are set forth to promote an understanding of thepresent invention through the embodiments, and the present invention isnot limited to the above-described specifications. The characteristicsof the flat uniform transmission lines of FIGS. 9 and 10, which will bedescribed later, are characteristics that were analyzed and measuredusing the flat uniform transmission line 40-1, which is designedaccording to the above-described specifications described with referenceto FIG. 5A.

FIG. 6A is a diagram showing the construction of a flat uniformtransmission line 40-2 according to a fifth embodiment of the presentinvention. FIG. 6B is a sectional view of the flat uniform transmissionline 40-2 according to FIG. 6A. The flat uniform transmission line 40-2has a structure in which three single signals are applied to the firstand second strip transmission lines 420-1 and 430-1 shown in FIG. 5A.Since the elements of the flat uniform transmission line 40-2 that arethe same as those of FIG. 5A have the same characteristics, detaileddescriptions thereof are omitted here.

As shown in FIG. 6A, the flat uniform transmission line 40-2 includes afirst strip transmission line 420-2 formed on a dielectric layer 405-2and a second strip transmission line 430-2 formed beneath the dielectriclayer 405-2.

More particularly, the first strip transmission line 420-2 includes afirst strip line 421-2, a second strip line 422-2, a third strip line423-2, a fourth strip line 424-2 and a fifth strip line 425-2. Thesecond strip transmission line 430-2 includes a first strip line 431-2,a second strip line 432-2, a third strip line 433-2, a fourth strip line434-2 and a fifth strip line 435-2.

Furthermore, the first and second strip transmission lines 420-2 and430-2 are respectively formed on the dielectric layer 405-2 and beneaththe dielectric layer 405-2, thereby minimizing the overall size of theflat uniform transmission line 40-2 and realizing broadband impedancecharacteristics.

In addition, the strip lines 421-2 - 425-2 and 431-2˜435-2, whichconstitute the first and second strip transmission lines 420-2 and430-2, have a constant width and thickness. The strip lines 421-2˜425-2and 431-2˜435-2 are spaced apart from one another at regular intervalsalong the length of the first and second strip transmission lines 420-2and 430-2, and are formed parallel to one another. Even if the flatuniform transmission line 40-2 is bent, the regular intervals betweenthe strip lines 421-2˜425-2 and 431-2˜435-2 are kept constant along thefirst and second strip transmission lines 420-2 and 430-2.

The first and second strip transmission lines 420-2 and 430-2 aresupplied with a first single signal, a second single signal and a thirdsingle signal at the same time. More particularly, the first strip line421-2 of the first strip transmission line 420-2 and the first stripline 431-2 of the second strip transmission line 430-2 are supplied withthe first single signal at the same time, the second strip line 422-2 ofthe first strip transmission line 420-2 and the second strip line 432-2of the second strip transmission line 430-2 are ground lines, and thethird strip line 423-2 of the first strip transmission line 420-2 andthe third strip line 433-2 of the second strip transmission line 430-2are supplied with the second single signal at the same time.Furthermore, the fourth strip line 424-2 of the first strip transmissionline 420-2 and the fourth strip line 434-2 of the second striptransmission line 430-2 are ground lines, and the fifth strip line 425-2of the first strip transmission line 420-2 and the fifth strip line435-2 of the second strip transmission line 430-2 are supplied with thethird single signal at the same time.

The first and second strip transmission lines 420-2 and 430-2 may bemade of any one material selected from among the materials having thesame characteristics as those of the first and second strip transmissionlines 420-1 and 430-1 of FIG. 5A.

FIG. 7 is a diagram showing differential impedance characteristics basedon FIG. 4A of the present invention. As described above in conjunctionwith the third embodiment, both FIGS. 7 and 8 are diagrams showingcharacteristics that were analyzed and measured using the flat uniformtransmission line 40, designed based on the detailed specifications ofrespective elements of FIG. 4A.

The results of the measurements of impedance of the flat uniformtransmission line 40 according to the third embodiment of FIG. 4A in afrequency band of 0 to 1 GHz are shown in FIG. 7.

As can be seen from FIG. 7, the impedance of the flat uniformtransmission line 40 according to the third embodiment falls within 10%(that is, an impedance error range of a 100 Ω over a differentialimpedance transmission line). Accordingly, the flat uniform transmissionline according to the present invention can realize the same broadbandimpedance characteristics, which cannot be realized in a high frequencyband.

FIG. 8 is a diagram showing insertion loss and the reflectioncoefficient characteristics based on FIG. 4A of the present invention.FIG. 8 shows the results of the measurements of the reflectioncoefficients and insertion losses of the flat uniform transmission line40 according to the third embodiment of FIG. 4A in a frequency band of 0to 1 GHz.

Here, the insertion loss is 0.02 dB at a frequency of 100 MHz when thelength of the first, second, fourth and fifth strip lines 421, 422, 424,425, 431, 432, 434 and 435 is 200 mm. Since the insertion loss isdefined as 22 dB/100 m at 100 MHz in the transmission specifications ofa UTP cable and the insertion loss is about 10 dB when the length of theflat uniform transmission line of the present invention is 100 m, it canbe seen that the insertion loss is improved significantly.

FIG. 9 is a diagram showing single impedance characteristics based onFIG. 5A of the present invention. Both FIGS. 9 and 10 are diagramsshowing characteristics that were analyzed and measured using the flatuniform transmission line 40-1, designed based on the detailedspecifications of respective elements of FIG. 5A.

The results of the measurements of the impedance of the flat uniformtransmission line 40-1 according to the fourth embodiment of FIG. 5A ata frequency band of 0 to 1 GHz are shown in FIG. 9.

Therefore, in the case of a 75 Ω coaxial cable for transmitting signalsat frequencies within a range of 54 MHz to 800 MHz, which is thefrequency band within which an HDTV is generally operated, transmissioncharacteristics can be secured when the cable has uniform impedancecharacteristics over the entire band. Accordingly, the flat uniformtransmission line according to the present invention can realize thesame broadband impedance characteristics.

FIG. 10 is a diagram showing insertion loss and the reflectioncoefficient characteristics based on FIG. 5A of the present invention.The results of the measurements of the reflection coefficient andinsertion loss of the flat uniform transmission line 40-1 according tothe fourth embodiment of FIG. 5A in a frequency band ranging from 0 to 1GHz are shown in FIG. 10.

Here, in the case of a 75 Ω coaxial cable for transmitting signals atfrequencies within a range of 54 MHz to 800 MHz, which is the frequencyband within which an HDTV is generally operated, the insertion loss per100 m is 25 dB or lower, and the reflection coefficient is 15 dB orhigher in the case of a general L-4CFB cable, even though they varydepending on the type of coaxial cable. Accordingly, the flat uniformtransmission line of the present invention has excellent characteristicswhen the length thereof is 100 m in that the insertion loss is 25 dB orlower and the reflection coefficient is about 15 dB.

The present invention provides a flat uniform transmission line havingan electromagnetic shielding function, which satisfies both thetransmission characteristics of a coaxial cable, used in a highfrequency band, and the characteristics of a twisted-pair cable, used ina low frequency band, and has excellent broadband impedancecharacteristics.

Furthermore, the present invention has advantages in that the overallsize of a flat uniform transmission line can be reduced through striplines formed in a double-layer fashion, and electromagnetic waves,radiated from the flat uniform transmission line, as well as externalnoise can be blocked because electromagnetic shielding layers areformed.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible without departing from the scope and spirit of the presentinvention as disclosed in the accompanying claims.

1. A flat uniform transmission line having an electromagnetic shieldingfunction, comprising: a strip transmission line formed on a dielectriclayer made of functional polymer material, the strip transmission linecomprising a plurality of strip lines, the plurality of strip linescomprising a first strip line configured to be a ground line, a secondstrip line supplied with a single signal, and a third strip lineconfigured to be a ground line; an insulating layer formed on the striptransmission line; and electromagnetic shielding layers respectivelyformed on the insulating layer and beneath the strip transmission line.2. The flat uniform transmission line as set forth in claim 1, whereinthe first strip line, the second strip line and the third strip line arespaced apart from one another at regular intervals that are keptconstant along a length of the strip transmission line.
 3. A flatuniform transmission line having an electromagnetic shielding function,comprising: a first strip transmission line formed on a dielectric layermade of functional polymer material in order to transmit signals, thefirst strip transmission line comprising a plurality of strip lines; asecond strip transmission line formed beneath the dielectric layer inorder to transmit signals, the second strip transmission line comprisinga plurality of strip lines; insulating layers respectively formed on thefirst strip transmission line and beneath the second strip transmissionline; and electromagnetic shielding layers respectively formed on theupper insulating layer and beneath the lower insulating layer.
 4. Theflat uniform transmission line as set forth in claim 3, wherein thefirst strip transmission line and the second strip transmission line aresimultaneously supplied with differential signals.
 5. The flat uniformtransmission line as set forth in claim 4, wherein the first striptransmission line comprises a first strip line supplied with a firstnegative differential signal, a second strip line supplied with a firstpositive differential signal, a third strip line configured to be aground line, a fourth strip line supplied with a second negativedifferential signal, and a fifth strip line supplied with a secondpositive differential signal.
 6. The flat uniform transmission line asset forth in claim 5, wherein the first to fifth strip lines,constituting the first strip transmission line, are spaced apart fromone another at regular intervals that are kept constant along a lengthof the first strip transmission line.
 7. The flat uniform transmissionline as set forth in claim 4, wherein the second strip transmission linecomprises a first strip line supplied with a first negative differentialsignal, a second strip line supplied with a first positive differentialsignal, a third strip line configured to be a ground line, a fourthstrip line supplied with a second negative differential signal, and afifth strip line supplied with a second positive differential signal. 8.The flat uniform transmission line as set forth in claim 7, wherein thefirst to fifth strip lines, constituting the second strip transmissionline, are spaced apart from one another at regular intervals that arekept constant along a length of the second strip transmission line. 9.The flat uniform transmission line as set forth in claim 3, wherein thefirst strip transmission line and the second strip transmission line aresimultaneously supplied with two single signals.
 10. The flat uniformtransmission line as set forth in claim 9, wherein the first striptransmission line comprises a first strip line configured to be a groundline, a second strip line supplied with a first single signal, a thirdstrip line configured to be a ground line, a fourth strip line suppliedwith a second single signal, and a fifth strip line configured to be aground line.
 11. The flat uniform transmission line as set forth inclaim 10, wherein the first to fifth strip lines, constituting the firststrip transmission line, are spaced apart from one another at regularintervals that are kept constant along a length of the first striptransmission line.
 12. The flat uniform transmission line as set forthin claim 9, wherein the second strip transmission line comprises a firststrip line configured to be a ground line, a second strip line suppliedwith a first single signal, a third strip line configured to be a groundline, a fourth strip line supplied with a second single signal, and afifth strip line configured to be a ground line.
 13. The flat uniformtransmission line as set forth in claim 12, wherein the first to fifthstrip lines, constituting the second strip transmission line, are spacedapart from one another at regular intervals that are kept constant alonga length of the second strip transmission line.
 14. The flat uniformtransmission line as set forth in claim 3, wherein the first striptransmission line and the second strip transmission line aresimultaneously supplied with three single signals.
 15. The flat uniformtransmission line as set forth in claim 14, wherein the first striptransmission line comprises a first strip line supplied with a firstsingle signal, a second strip line configured to be a ground line, athird strip line supplied with a second single signal, a fourth stripline configured to be a ground line, and a fifth strip line suppliedwith a third single signal.
 16. The flat uniform transmission line asset forth in claim 15, wherein the first to fifth strip lines,constituting the first strip transmission line, are spaced apart fromone another at regular intervals that are kept constant along a lengthof the first strip transmission line.
 17. The flat uniform transmissionline as set forth in claim 14, wherein the second strip transmissionline comprises a first strip line supplied with a first single signal, asecond strip line configured to be a ground line, a third strip linesupplied with a second single signal, a fourth strip line configured tobe a ground line, and a fifth strip line supplied with a third singlesignal.
 18. The flat uniform transmission line as set forth in claim 17,wherein the first to fifth strip lines, constituting the second striptransmission line, are spaced apart from one another at regularintervals that are kept constant along a length of the second striptransmission line.
 19. The flat uniform transmission line as set forthin claim 3, wherein the insulating layer comprises a first insulatinglayer formed on the first strip transmission line and a secondinsulating layer formed beneath the second strip transmission line. 20.The flat uniform transmission line as set forth in claim 3, wherein theelectromagnetic shielding layers comprise a first electromagneticshielding layer formed on the first insulating layer and a secondelectromagnetic shielding layer formed beneath the second insulatinglayer.
 21. A flat uniform transmission line having an electromagneticshielding function, comprising: a first strip transmission line formedon a dielectric layer made of functional polymer material in order totransmit signals, the first strip transmission line comprising a firststrip line supplied with a first negative differential signal, a secondstrip line supplied with a first positive differential signal, a thirdstrip line configured to be a ground line, a fourth strip line suppliedwith a second negative differential signal, and a fifth strip linesupplied with a second positive differential signal; a second striptransmission line formed beneath the dielectric layer in order totransmit signals, the second strip line comprising a first strip linesupplied with the first negative differential signal, a second stripline supplied with the first positive differential signal, a third stripline configured to be a ground line, a fourth strip line supplied withthe second negative differential signal, and a fifth strip line suppliedwith the second positive differential signal; a first insulating layerformed on the first strip transmission line; a second insulating layerformed beneath the second strip transmission line; and electromagneticshielding layers respectively formed on the first insulating layer andbeneath the second insulating layer.
 22. A flat uniform transmissionline having an electromagnetic shielding function, comprising: a firststrip transmission line formed on a dielectric layer made of functionalpolymer material in order to transmit signals, the first striptransmission line comprising a first strip line supplied with a firstnegative differential signal, a second strip line supplied with a firstpositive differential signal, a third strip line configured to be aground line, a fourth strip line supplied with a second negativedifferential signal, and a fifth strip line supplied with a secondpositive differential signal; a second strip transmission line formedbeneath the dielectric layer in order to transmit signals, the secondstrip transmission line comprising a first strip line supplied with thefirst negative differential signal, a second strip line supplied withthe first positive differential signal, a third strip line configured tobe a ground line, a fourth strip line supplied with the second negativedifferential signal, and a fifth strip line supplied with the secondpositive differential signal; insulating layers respectively formed onthe first strip transmission line and beneath the second striptransmission line; a first electromagnetic shielding layer formed on theupper insulating layer; and a second electromagnetic shielding layerformed beneath the lower insulating layer.
 23. A flat uniformtransmission line having an electromagnetic shielding function,comprising: a first strip transmission line formed on a dielectric layermade of functional polymer material in order to transmit signals, thefirst strip transmission line comprising a first strip line suppliedwith a first negative differential signal, a second strip line suppliedwith a first positive differential signal, a third strip line configuredto be a ground line, a fourth strip line supplied with a second negativedifferential signal, and a fifth strip line supplied with a secondpositive differential signal; a second strip transmission line formedbeneath the dielectric layer in order to transmit signals, the secondstrip transmission line comprising a first strip line supplied with thefirst negative differential signal, a second strip line supplied withthe first positive differential signal, a third strip line configured tobe a ground line, a fourth strip line supplied with the second negativedifferential signal, and a fifth strip line supplied with the secondpositive differential signal; a first insulating layer formed on thefirst strip transmission line; a second insulating layer formed beneaththe second strip transmission line; a first electromagnetic shieldinglayer formed on the first insulating layer; and a second electromagneticshielding layer formed beneath the second insulating layer.
 24. A flatuniform transmission line having an electromagnetic shielding function,comprising: a first strip transmission line formed on a dielectric layermade of functional polymer material in order to transmit signals, thefirst strip transmission line comprising a first strip line configuredto be a ground line, a second strip line supplied with a first singlesignal, a third strip line configured to be a ground line, a fourthstrip line supplied with a second single signal, and a fifth strip lineconfigured to be a ground line; a second strip transmission line formedbeneath the dielectric layer in order to transmit signals, the secondstrip transmission line comprising a first strip line configured to be aground line, a second strip line supplied with the first single signal,a third strip line configured to be a ground line, a fourth strip linesupplied with the second single signal, and a fifth strip lineconfigured to be a ground line; a first insulating layer formed on thefirst strip transmission line; a second insulating layer formed beneaththe second strip transmission line; and an electromagnetic shieldinglayer formed on the first insulating layer and beneath the secondinsulating layer.
 25. A flat uniform transmission line having anelectromagnetic shielding function, comprising: a first striptransmission line formed on a dielectric layer made of functionalpolymer material in order to transmit signals, the first striptransmission line comprising a first strip line configured to be aground line, a second strip line supplied with a first single signal, athird strip line configured to be a ground line, a fourth strip linesupplied with a second single signal, and a fifth strip line configuredto be a ground line; a second strip transmission line formed beneath thedielectric layer in order to transmit signals, the second striptransmission line comprising a first strip line configured to be aground line, a second strip line supplied with the first single signal,a third strip line configured to be a ground line, a fourth strip linesupplied with the second single signal, and a fifth strip lineconfigured to be a ground line; an insulating layer formed on the firststrip transmission line and beneath the second strip transmission line;a first electromagnetic shielding layer formed on the insulating layer;and a second electromagnetic shielding layer formed beneath theinsulating layer.
 26. A flat uniform transmission line having anelectromagnetic shielding function, comprising: a first striptransmission line formed on a dielectric layer made of functionalpolymer material in order to transmit signals, the first striptransmission line comprising a first strip line configured to be aground line, a second strip line supplied with a first single signal, athird strip line configured to be a ground line, a fourth strip linesupplied with a second single signal, and a fifth strip line configuredto be a ground line; a second strip transmission line formed beneath thedielectric layer in order to transmit signals, the second striptransmission line comprising a first strip line configured to be aground line, a second strip line supplied with the first single signal,a third strip line configured to be a ground line, a fourth strip linesupplied with the second single signal, and a fifth strip lineconfigured to be a ground line; a first insulating layer formed on thefirst strip transmission line; a second insulating layer formed beneaththe second strip transmission line; a first electromagnetic shieldinglayer formed on the first insulating layer; and a second electromagneticshielding layer formed beneath the second insulating layer.
 27. A flatuniform transmission line having an electromagnetic shielding function,comprising: a first strip transmission line formed on a dielectric layermade of functional polymer material in order to transmit signals, thefirst strip transmission line comprising a first strip line suppliedwith a first single signal, a second strip line configured to be aground line, a third strip line supplied with a second single signal, afourth strip line configured to be a ground line, and a fifth strip linesupplied with a third single signal; a second strip transmission lineformed beneath the dielectric layer in order to transmit signals, thesecond strip transmission line comprising a first strip line suppliedwith the first single signal, a second strip line configured to be aground line, a third strip line supplied with the second single signal,a fourth strip line configured to be a ground line, and a fifth stripline supplied with the third single signal; a first insulating layerformed on the first strip transmission line; a second insulating layerformed beneath the second strip transmission line; and electromagneticshielding layers respectively formed on the first insulating layer andbeneath the second insulating layer.
 28. A flat uniform transmissionline having an electromagnetic shielding function, comprising: a firststrip transmission line formed on a dielectric layer made of functionalpolymer material in order to transmit signals, the first striptransmission line comprising a first strip line supplied with a firstsingle signal, a second strip line configured to be a ground line, athird strip line supplied with a second single signal, a fourth stripline configured to be a ground line, and a fifth strip line suppliedwith a third single signal; a second strip transmission line formedbeneath the dielectric layer in order to transmit signals, the secondstrip transmission line comprising a first strip line supplied with thefirst single signal, a second strip line configured to be a ground line,a third strip line supplied with the second single signal, a fourthstrip line configured to be a ground line, and a fifth strip linesupplied with the third single signal; insulating layers respectivelyformed on the first strip transmission line and beneath the second striptransmission line; a first electromagnetic shielding layer formed on theinsulating layer; and a second electromagnetic shielding layer formedbeneath the insulating layer.
 29. A flat uniform transmission linehaving an electromagnetic shielding function, comprising: a first striptransmission line formed on a dielectric layer made of functionalpolymer material in order to transmit signals, the first striptransmission line comprising a first strip line supplied with a firstsingle signal, a second strip line configured to be a ground line, athird strip line supplied with a second single signal, a fourth stripline configured to be a ground line, and a fifth strip line suppliedwith a third single signal; a second strip transmission line formedbeneath the dielectric layer in order to transmit signals, the secondstrip transmission line comprising a first strip line supplied with thefirst single signal, a second strip line configured to be a ground line,a third strip line supplied with the second single signal, a fourthstrip line configured to be a ground line, and a fifth strip linesupplied with the third single signal; a first insulating layer formedon the first strip transmission line; a second insulating layer formedbeneath the second strip transmission line; a first electromagneticshielding layer formed on the first insulating layer; and a secondelectromagnetic shielding layer formed beneath the second insulatinglayer.